<template>
  <div class="CameraIn">
    <video
      id="videoCamera"
      width="95%"
      height="95%"
      autoplay
      style="background-color: rgba(68, 142, 252, 0.1)"
    ></video>
    <canvas
      style="display: none"
      id="canvasCamera"
      width="1200"
      height="800"
    ></canvas>
  </div>
</template>

<script>
export default {
  name: "CameraIn",
  props: ["camera_in"],
  data() {
    return {
      imgSrc: "",
      thisCancas: null,
      thisContext: null,
      thisVideo: null,
    };
  },
  methods: {
    //获取当前时间
    getNowTime() {
      let date = new Date();
      let year = date.getFullYear();
      let month = date.getMonth() + 1;
      let day = date.getDate();
      let hour = date.getHours();
      let minute = date.getMinutes();
      let second = date.getSeconds();
      let time =
        year +
        this.addZero(month) +
        this.addZero(day) +
        "-" +
        this.addZero(hour) +
        this.addZero(minute) +
        this.addZero(second);
      return time;
    },
    //小于10的拼接上0字符串
    addZero(s) {
      return s < 10 ? "0" + s : s;
    },
    // 调用权限（打开摄像头功能）
    getCompetence() {
      var _this = this;
      this.thisCancas = document.getElementById("canvasCamera");
      this.thisContext = this.thisCancas.getContext("2d");
      this.thisVideo = document.getElementById("videoCamera");
      // 旧版本浏览器可能根本不支持mediaDevices，我们首先设置一个空对象
      if (navigator.mediaDevices === undefined) {
        navigator.mediaDevices = {};
      }
      // 一些浏览器实现了部分mediaDevices，我们不能只分配一个对象
      // 使用getUserMedia，因为它会覆盖现有的属性。
      // 这里，如果缺少getUserMedia属性，就添加它。
      if (navigator.mediaDevices.getUserMedia === undefined) {
        navigator.mediaDevices.getUserMedia = function (constraints) {
          // 首先获取现存的getUserMedia(如果存在)
          var getUserMedia =
            navigator.webkitGetUserMedia ||
            navigator.mozGetUserMedia ||
            navigator.getUserMedia;
          // 有些浏览器不支持，会返回错误信息
          // 保持接口一致
          if (!getUserMedia) {
            return Promise.reject(
              new Error("getUserMedia is not implemented in this browser")
            );
          }
          // 否则，使用Promise将调用包装到旧的navigator.getUserMedia
          return new Promise(function (resolve, reject) {
            getUserMedia.call(navigator, constraints, resolve, reject);
          });
        };
      }
      var constraints = {
        audio: false,
        video: {
          width: "100%",
          height: "100%",
          transform: "scaleX(-1)",
        },
      };
      navigator.mediaDevices
        .getUserMedia(constraints)
        .then(function (stream) {
          // 旧的浏览器可能没有srcObject
          if ("srcObject" in _this.thisVideo) {
            _this.thisVideo.srcObject = stream;
          } else {
            // 避免在新的浏览器中使用它，因为它正在被弃用。
            _this.thisVideo.src = window.URL.createObjectURL(stream);
          }
          _this.thisVideo.onloadedmetadata = function (e) {
            _this.thisVideo.play();
            setTimeout(() => {
              _this.setImage();
            }, 8000);
          };
        })
        .catch((err) => {
          console.log(err);
        });
    },

    //  绘制图片（拍照功能）
    setImage() {
      let _this = this;
      const nowTime = this.getNowTime();
      const filename = `${nowTime}.png`;
      // 点击，canvas画图
      _this.thisContext.drawImage(_this.thisVideo, 0, 0, 1200, 800);
      // 获取图片base64链接
      let image = this.thisCancas.toDataURL("image/png");
      //转文件
      const imageFile = this.dataURLtoFile(image, filename);
      this.$message("开始识别，请稍等");
      let formData = new FormData();
      formData.append("file", imageFile);
      this.axios
        .post("/discern/sendCarPlate-In", formData)
        .then((res) => {
          if (res.data.code == "200") {
            this.$message({
              message: `车牌号码：${res.data.data.number}进场`,
              type: "success",
            });
          } else {
            this.$message.error("车牌识别失败");
          }
        })
        .catch((err) => {
          this.$message.error("车牌识别失败");
          console.err(err);
        });
    },

    // base64转文件
    dataURLtoFile(dataurl, filename) {
      var arr = dataurl.split(",");
      var mime = arr[0].match(/:(.*?);/)[1];
      var bstr = atob(arr[1]);
      var n = bstr.length;
      var u8arr = new Uint8Array(n);
      while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
      }
      return new File([u8arr], filename, { type: mime });
    },
    // 关闭摄像头
    stopNavigator() {
      this.thisVideo.srcObject.getTracks()[0].stop();
    },
  },
  watch: {
    camera_in: {
      handler(newVal, oldVal) {
        newVal ? this.getCompetence() : this.stopNavigator();
      },
      deep: true,
    },
  },
};
1;
</script>

<style scoped>
.CameraIn {
  margin-left: 2%;
  width: 96%;
  height: 80%;
}
</style>